1. Field of the Invention
The present invention relates to a hand shake blur correcting apparatus.
2. Description of the Related Art
A still image hand shake blur correction technique is a technique for reducing hand shake blur in still image shooting, and is achieved by detecting the hand shake blur and stabilizing the image based on the detected result.
A method of detecting the hand shake blur includes a method of using a hand shake blur sensor (angular velocity sensor), and an electronic method of detecting by analyzing the image. The method of stabilizing the image may be an optical method in which the lens and imaging sensors are stabilized, or an electronic method in which the blur caused by hand shake is removed through image processing.
The completely electronic hand shake blur correction technique, that is, a technique of generating the image in which hand shake blur is removed by analyzing and processing only one photographed hand shake blur image has not reached the practical level. In particular, obtaining a hand shake blur signal of a precision obtained by a hand shake blur sensor is difficult by analyzing one hand shake blur image.
Therefore, it is realistic to detect the hand shake blur using the hand shake blur sensor, and to remove the hand shake blur through image processing using the hand shake blur data. The removal of blur through image processing is referred to as image restoration. The method including the hand shake blur sensor and the image restoration is herein referred to as an electronic hand shake blur correction. A method of correcting the image by detecting the hand shake blur using the hand shake blur sensor and driving the optical system (lens, imaging sensors) is referred to as an optical hand shake blur correction. The electronic hand shake blur correction has merits in terms of cost, size, power consumption compared to the optical hand shake blur correction. The present invention relates to the electronic hand shake blur correction.
If the degradation process of the image such as hand shake blur and out of focus is definite, the degradation can be alleviated by using an image restoration filter referred to as a Wiener filter or a generalized inverse filter. The image restoration filter is generally configured by a two-dimensional FIR filter. When the hand shake blur correction device is realized with a hardware, the size of the two-dimensional FIR filter has the upper limit value of the tap size fixed due to the restriction of the hardware. Thus, when the hand shake blur size becomes large to greater than or equal to a constant value, all the coefficient components of the image restoration filter cannot fall within the number of taps of the two-dimensional FIR filter, and the corrective effect lowers. Thus, the upper limit value of the hand shake blur size that can be performed with image restoration becomes limited.